1. Field of the Invention
The present invention relates to a scroll-type variable-capacity compressor suitable for use as a refrigerant compressor of an automobile air-conditioner, for example, in particular relates to the variable-capacity mechanism of the same.
2. Description of the Related Art
As the variable-capacity mechanisms of conventional scroll compressors, as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 59-105994 and Japanese Unexamined Utility Model Publication (Kokai) No. 62-90901, a plurality of bypass holes are made in an end plate of a stationary scroll member and a plurality of plunger valves or spool valves are provided to independently open and close the bypass holes.
Since the variable-capacity mechanisms of these conventional scroll compressors had a plunger valve or spool valve provided for each of the plurality of bypass holes, there was the problem that there were a large number of parts, constructions was complicated, and the processability and the assembly ability were poor. In prior art devices, further, as is clear from their drawings, a pair of bypass valves were provided at positions symmetrical to the center of the stationary scroll member so as to enable the bypass holes to be opened and closed at the same timing for a pair of operating spaces. This reduced the number of stages of changes in the discharge capacity of the compressors. Therefore, if the compressors of the prior art devices are used for something like the refrigerant compressor of an automobile air-conditioner where the rotational speed of the drive and the cooling load vary over a wide range, the problem arises that it is difficult to maintain the discharge capacity constant in the face of these changes or to change the discharge capacity smoothly.
Further, it is difficult to provide the bypass holes at positions near the center portion of the end plate of the stationary scroll member, so in the prior art there was the problem that it was difficult to bring the minimum discharge capacity of the scroll compressor sufficiently near 0 percent. Further, when the compressor is turning at a high speed, if the opening time of the bypass holes becomes shorter, there is the problem that it no longer becomes possible to sufficiently cause bypassing of the compressed fluid in the operating spaces between the two scroll members and thus a small capacity cannot be realized. The present invention has as its object the resolution of these problems.